Conventional lithography techniques used in the manufacturing process of semiconductor devices include the double patterning technique by ArF immersion exposure, EUV lithography, and nano imprints. The conventional lithography techniques have various problems, such as increased costs and decreased throughput caused by the refinement of patterns.
Under such conditions, application of DSA (directed self-assembly) to lithography techniques is expected. Since directed self-assembly is generated by spontaneous energy stability, this enables the formation of patterns with high dimensional accuracy. Especially for technologies using microphase separation of macromolecule block copolymer, periodic structures up to several hundred nanometers (nm) of various shapes may be formed with a simple coating and annealing process. Depending on the composition ratio of the macromolecule block copolymer, spherical shapes, cylindrical shapes, or lamellar shapes may be formed by changing the sizes based on the molecular weight, and a dot pattern, hole or pillar pattern, or a line pattern of various dimensions may be formed on a substrate.
In order to form a desired pattern in a wide range using DSA, a guide to control the generating position of the DSA polymer phase needs to be provided. A physical guide (grapho-epitaxy) has a relief structure with a phase-separation pattern formed on the surface. A chemical guide (chemical-epitaxy) is formed on the lower layer of the DSA material. Based on the surface energy difference, control of the forming position of the microphase separation pattern is achieved.
Several chemical guide formation methods are known; however, many of these guides contain physical steps with sizes up to 10 nm. This physical step makes it difficult to transcribe a microphase separation pattern on the lower layer of the processed film, which causes detrimental effects to the regularity of the phase separation.